System for efficiently cooling a processor

ABSTRACT

One embodiment of a system for efficiently cooling a processor includes an active hybrid heat transport module adapted to be integrated with a fansink. The hybrid heat transport module comprises both a fluid channel and an air channel adapted for transporting heat. The hybrid heat transport module and the fansink may be used alone or in combination to dissipate heat from the processor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/822,958, filed Apr. 12, 2004 now U.S. Pat. No. 7,359,197.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to computer hardware and moreparticularly to a system for efficiently cooling a processor.

2. Description of the Background Art

FIG. 1 is an isometric view illustrating a prior art system 100 used tocool a processor (not shown). As shown, system 100 characteristicallyincludes a heat sink assembly 104, which further includes a fan 106,walls 109 and a bottom plate 111. Typically, system 100 is thermallycoupled to a processor, for example using thermal adhesive havingthermal properties that facilitate transferring heat generated by theprocessor to bottom plate 111 of heat sink assembly 104. System 100 mayalso include a heat sink lid (not shown), which, among other things,prevents particles and other contaminants from entering fan 106 and airblown from fan 106 from escaping system 100. Heat sink lid 102, togetherwith walls 109 and bottom plate 111 of heat sink assembly 104, define aplurality of air channels 108.

Fan 106 is configured to force air through air channels 108 such thatthe heat generated by the processor transfers to the air as the airpasses over bottom plate 111. The heated air then exits heat sinkassembly 104, as depicted by flow lines 114, thereby dissipating theheat generated by the processor into the external environment. Thisprocess cools the processor and, among other things, prevents theprocessor from burning up during operation. Persons skilled in the artwill understand that air channels 108 typically are configured to directair blown from fan 106, over bottom plate 111, to the externalenvironment in a manner that most efficiently removes heat from theprocessor.

One drawback of using system 100 to cool a processor is that a soundwave produced when fan 106 forces air through an air channel 108oftentimes establishes a standing wave within air channel 108. Aspersons skilled in the art will understand, this phenomenonsubstantially increases the noise level of the airflow through airchannel 108 because the resulting standing wave produced by theinterference between an incident sound wave and a reflected sound wavehas an amplitude at the antinodes that is substantially greater than theamplitude of incident sound wave. The increased noise is particularlyannoying to persons who use computers and other electronic devices thatinclude a system similar to system 100.

One method for reducing airflow noise while cooling a processor is toimplement a fluid-based cooling system, in which heat generated by theprocessor transfers to a heat transfer fluid (such as water) beingquickly circulated close to the processor. However, typical fluidcooling systems are driven by large pumps, which are prone to frequentfailure and tend to consume a great deal of power. Moreover, suchsystems tend to use large quantities of fluid, circulating at a highflow rate, and therefore must be frequently replenished or replaced.

Thus, there is a need in the art for a system for efficiently cooling aprocessor.

SUMMARY OF THE INVENTION

One embodiment of a system for efficiently cooling a processor includesan active hybrid heat transport module adapted to be integrated with afansink. The hybrid heat transport module comprises both a fluid channeland an air channel adapted for transporting heat. The hybrid heattransport module and the fansink may be used alone or in combination todissipate heat from the processor.

One advantage of the disclosed system is that, among other things, thesystem produces less airflow noise during operation.

A second advantage of the disclosed system is that it is more reliablethan conventional fluid cooling systems.

A third advantage of the disclosed system is that it dissipates heatmore effectively and more efficiently than conventional fan- orfluid-based cooling systems

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view illustrating a prior art system used to coola processor.

FIG. 2 is schematic diagram illustrating a computing device adapted foruse with a system for cooling a processor, according to one embodimentof the present invention.

FIG. 3 is an isometric view illustrating an improved system for coolinga processor, according to one embodiment of the present invention.

FIG. 4 is an exploded view of a portion of the cooling systemillustrated in FIG. 3;

FIG. 5 is a cross sectional view of a portion of the cooling systemillustrated in FIG. 3; and

FIG. 6 is a flow diagram illustrating a method for controlling thecooling system illustrated in FIG. 3, according to one embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 is schematic diagram illustrating a computing device 200 adaptedfor use with a system 218 for cooling a processor, according to oneembodiment of the present invention. Computing device 200 may be anytype of computing device, including, without limitation, a desktopcomputer, a server, a laptop computer, a palm-sized computer, a personaldigital assistant (PDA), a tablet computer, a gaming console, a cellulartelephone, a computer-based simulator and the like.

As shown, computing device 200 includes a housing 201, within which amotherboard 204 resides. Mounted on motherboard 204 are a centralprocessing unit (CPU) 206, a processor cooler 208 for cooling CPU 206, asystem fan 210 for removing heat from computing device 200, and one ormore peripheral component interface (PCI) cards 212, each interfacedwith a slot located in the back part of housing 201. Motherboard 204further incorporates a graphics card 202 that enables computing device200 to rapidly process graphics related data for graphics intensiveapplication, such as gaming applications. Graphics card 202 comprises aprinted circuit board (PCB) upon which a plurality of circuit components(not shown), such as memory chips and the like, are mounted. Inaddition, graphics card 200 includes a graphics processing unit (GPU)216, mounted to one face of graphics card 202, for processing graphicsrelated data. Generally, cooling system 218 is configured for couplingto GPU 216 in lieu of a conventional cooling system, such as coolingsystem 100 of FIG. 1.

FIG. 3 is an isometric view illustrating an improved system 300 forcooling a processor, according to one embodiment of the presentinvention. Similar to system 218 of FIG. 2, cooling system 300 may beadapted for use in any type of appropriate computing device. As shown,cooling system 300 may include, without limitation, a fanksink 302 and ahybrid heat transport module 304. As described in further detail below,fansink 302 and hybrid heat transport module 304 may operateindependently or in combination to dissipate heat from a processor.

In one embodiment, fansink 302 is configured in a manner similar tocooling system 100 of FIG. 1 and includes, without limitation, a fan308, walls 306 and a bottom plate 318. In one embodiment, system 100also includes a heat sink lid 320, which, among other things, preventsparticles and other contaminants from entering fan 308 and air blownfrom fan 308 from escaping system 300. Heat sink lid 320, together withwalls 306 and bottom plate 318 of fansink 302, define a plurality of airchannels 322.

Hybrid heat transport module 304 is adapted to be integrated withfansink 302. In one embodiment, hybrid heat transport module 304 isthermally coupled to a portion of bottom plate 318 and includes, withoutlimitation, a fluid channel 312, an inlet 314, an outlet 316 and aplurality of air channels 310. Hybrid heat transport module 304 iscoupled to a pump, which is adapted for circulating a heat transferfluid (e.g., water or any other suitable heat conducting fluid) througha closed loop, including fluid channel 312. In one embodiment, the pumpcirculates fluid from hybrid heat transport module 304 through a heatexchanger prior to supplying the fluid back to hybrid heat transportmodule 304. Inlet 314 and outlet 316 are configured for respectivelysupplying and removing the heat transfer fluid to fluid channel 312.

In one embodiment, air channels 310 are adapted for coupling to airchannels 322 and for transporting forced air from fan 308. In oneembodiment, air channels 310 are positioned over and around fluidchannel 312, so that fluid channel 312 is substantially enclosed withinair channels 310. In alternative embodiment, fluid channel 312 and airchannels 310 may be positioned in any relative orientation that providesgood heat dissipation. Those skilled in the art will recognize thathybrid heat transport module 304 may be implemented to transfer heat viaair channels 310, fluid channel 312, or both in combination.

In one embodiment, fansink 302 dissipates heat in a manner similar tosystem 100 illustrated in FIG. 1. Fan 308 is configured to force airthrough air channels 322 and air channels 310 such that the heatgenerated by the processor transfers to the air as the air passes overbottom plate 318. The heated air then exits system 300, as depicted byflow lines 324, thereby dissipating the heat generated by the processorinto the external environment.

In one embodiment, the pump circulates the heat transfer fluid throughfluid channel 312 of hybrid heat transport module 304, and heatgenerated by the processor transfers to the circulating heat transferfluid as well as to air in air channels 310. Fluid channel 312 isadapted for transporting heat transfer fluid through a downstream heatexchanger, which dissipates heat from the heat transfer fluid into anoutside environment.

Persons skilled in the art will recognize that system 300, includingfansink 302 and hybrid heat transport module 304, may be used to coolany type of processor. For example, in one embodiment, the processorcomprises a graphics processing unit. In an alternative embodiment, theprocessor may comprise a central processing unit. In yet anotheralternative embodiment, the processor may comprise anapplication-specific integrated circuit (ASIC). In another embodiment,system 300 may be sized to cool a memory chip in addition to theprocessor.

FIG. 4 is an exploded view of a portion of cooling system 300. In oneembodiment, bottom plate 318 includes a trench 402 sized for coupling toand sealing fluid channels 312. In one embodiment, the surface of trench402 is textured to increase the heat transfer surface area of bottomplate 318, as described in further detail below, and to transfer heatfrom bottom plate 318 to the heat transfer fluid flowing through fluidchannel 312. For example, trench 402 may further include a plurality ofpins 404 extending upward from bottom plate 318. The density andgeometric shape of pins 404 may vary, so long as pins 404 are capable ofeffectively transferring heat from bottom plate 318 to the heat transferfluid flowing around pins 404.

FIG. 5 is a cross sectional view of hybrid heat transport module 304,taken along sectional line 3-3′ of FIG. 3. As illustrated, hybrid heattransport module 304 is configured to dissipate heat from a processorvia fluid channel 312 and/or air channels 310. As described above, airchannels 310 may be configured to interface to air channels 322 offansink 302, so that even when the pump is not activated to circulatefluid through fluid channel 312, air channels 310 will operate toincrease the heat transfer surface area of system 300 (e.g., byeffectively extending air channels 322), thereby enabling heat to bedissipated more efficiently.

Fansink 302 and hybrid heat transport module 304 may be implementedindependently or in combination to dissipate heat from a processor, inorder to dissipate heat from the processor in the most efficient manner.For example, fansink 302 may be implemented to dissipate a majority ofthe generated heat, hybrid fluid heat transport module 304 may beimplemented to dissipate a smaller quantity of heat, and the proportionsof heat dissipated by fansink 302 and hybrid heat transport module 304may be dynamically adjusted. Alternatively, one of fansink 302 andhybrid heat transport module 304 may be implemented as a primary meansfor heat dissipation, while the other mechanism is implemented on anas-needed basis to dissipate excess heat.

FIG. 6 is a flow diagram illustrating a method 600 for controllingcooling system 300, for example for implementation by a control unitcoupled to cooling system 300, according to one embodiment of theinvention. In the illustrated embodiment, the method 600 implementsfansink 302 as a primary means for heat dissipation, while hybrid heattransport module 304 is implemented on as as-needed basis. Method 600 isinitialized at step 602 and proceeds to step 604, where method 600monitors the temperature of the processor, for example by means of athermal diode or other sensor positioned proximate to the processor.Method 600 then proceeds to step 606 and determines whether thetemperature of the processor has reached a predetermined thresholdtemperature at which a secondary heat dissipation mechanism (e.g.,hybrid heat transport module 304) should be implemented.

If method 600 determines at step 606 that the processor temperature hasnot reached the threshold temperature, method 600 returns to step 604and continues to monitor the processor temperature. Alternatively, ifmethod 600 determines at step 606 that the threshold temperature hasbeen reached or exceeded, method 600 proceeds to step 608 and turns onthe pump of hybrid heat transport module 304, in order to engage thesecondary heat dissipation mechanism. Method 600 then determines at step610 whether the implementation of hybrid heat transport module 304 hascooled the processor to a predetermined desired temperature (e.g., anideal operating temperature).

If method 600 determines at step 610 that the processor has been cooledto the desired temperature, method 600 proceeds to step 612 and turnsoff the pump of hybrid heat transport module 304, effectively shuttingoff hybrid heat transport module 304 so that the processor continues tobe cooled by the primary heat dissipation mechanism (e.g., fansink 302).Method 600 then returns to step 604 and continues to monitor thetemperature of the processor. Alternatively, if method 600 determines atstep 610 that the processor has not yet been cooled to the desiredtemperature, method 600 returns to step 608 and continues to run thepump of hybrid heat transport module 304 until the processor is cooledto the desired temperature.

Cooling system 300 offers several advantages over conventional coolingsystems, such as cooling system 100 of FIG. 1. First, using fansink 302in conjunction with hybrid heat transport module 304 results in a morereliable cooling system, because the pump of hybrid heat transportmodule 304 may be implemented on a limited or as-needed basis. The lifeof the pump is thereby extended, because the pump is not constantlyoperating at maximum power. For example, in one embodiment, the life ofa typical pump may be extended by approximately fifty percent.Alternatively, cooling system 300 may incorporate a pump that issignificantly smaller than a pump typically incorporated in afluid-based cooling system. Moreover, in the event of failure, fansink302 may operate as a backup to fluid heat transport module 304, and viceversa.

Also, because hybrid heat transport module 304 may be implemented on alimited or as-needed basis (e.g., as opposed to being a primary heatdissipation means), the amount of heat transfer fluid and the flow rateof the fluid through fluid channel 312 may be reduced compared to aconventional fluid-based cooling system. Thus, cooling system 300requires less maintenance (e.g., frequent replenishment of fluidreservoirs) than conventional fluid-based cooling systems, and the pumpconsumes less power.

In addition, because cooling system 300 relies less on fansink 302 todissipate heat (e.g., when hybrid heat transport module 304 isimplemented either alone or in conjunction with fansink 302), anamplitude at the antinodes of interfering sound waves established withinair channel 322 is smaller. Thus, the noise level of the airflow throughair channel 322 may be substantially decreased.

Moreover, using hybrid heat transport module 304 in conjunction withfansink 302 increases the heat flow rate, (dQ/dT), of cooling system300, which enables cooling system 300 to transfer heat away from theprocessor more efficiently than conventional cooling systems. One reasonfor this increase is that the heat transfer area, A, of cooling system300 can be substantially larger than that of conventional coolingsystems, owing to the incorporation of air channels 310 and pins 404.Even if hybrid heat transport module 304 is not active (e.g., the pumpis not activated), the configuration of hybrid heat transport module 304will increase the heat transfer surface area over which air forced byfan 308 travels, as the forced air will travel through both channels 322and channels 310.

Heat flow rate (dQ/dT) is calculated according to the followingequation:(dQ/dT)=hA(T _(sink) −T _(air))  (EQN. 1)where h is the heat transfer coefficient of cooling system 300, T_(sink)is the temperature of the heat exchanging elements (e.g., air channels322, air channels 310 and pins 404) and T_(air) is the temperature ofthe air flowing through the heat exchanging elements. As discussedabove, since A is much larger for cooling system 300 than for aconventional cooling system (and ΔT is approximately the same), the heatflow rate (dQ/dT) is substantially increased when using cooling system300.

The increased heat flow rate (dQ/dT) further results in cooling system300 having an improved heat transfer efficiency, ⊖_(sa), relative toconventional cooling systems. As persons skilled in the art willrecognize, heat transfer efficiency, ⊖_(sa), may be calculated accordingto the following equation:⊖_(sa)=(T _(sink) −T _(air))/(dQ/dT)(° C./watt)  (EQN. 2)where a smaller value for ⊖_(sa) indicates increased efficiency andtherefore is more desirable. Again, the larger heat transfer area, A,causes cooling system 300 to have greater heat flow rate (dQ/dT), and,consequently, an improved efficiency as well (as evidenced by thesmaller value of ⊖_(sa)).

Simulations comparing improved cooling system 300 with a conventionalcooling system show that improved cooling system 300 can cool aprocessor to temperatures that are upwards of twenty-two percent lowerthan temperatures achieved with the conventional cooling system, withoutsubstantially increasing power consumption.

The location of cooling system 300, fansink 302 and hybrid heattransport module 304, as well as the size and shape of the components,may be dictated by other board mounted components, as well as byaccelerated graphics processor (AGP)-specified envelope constraints.Moreover, those skilled in the art will appreciate that the coolingsystem described herein may be implemented in both ATX motherboardconfigurations (wherein a graphics card is orientated so that the GPUfaces downward relative to the computing device, as illustrated in FIG.2) and BTX configurations (wherein a graphics card is orientated so thatthe GPU faces upward relative to the computing device). Therefore, thecooling system of the present invention may be implemented as asingle-slot cooling solution, e.g., wherein the size of the coolingsystem does not require space on the motherboard that may be allocatedto other components, such as PCI cards.

Thus, the present invention represents a significant advancement in thefield of processor cooling. By implementing a hybrid heat transportmodule in conjunction with a fansink, a system used to cool a coolingsystem will produce less airflow noise in operation than systems thatincorporate conventional heat sink lids and will cool a processor moreeffectively and efficiently. Moreover, by implementing the hybrid heattransport module on a limited basis, the life of a pump used to drive aportion of the hybrid heat transport module can be significantlyextended.

Although the invention has been described above with reference tospecific embodiments, persons skilled in the art will understand thatvarious modifications and changes may be made thereto without departingfrom the broader spirit and scope of the invention as set forth in theappended claims. The foregoing description and drawings are,accordingly, to be regarded in an illustrative rather than a restrictivesense.

1. A system for cooling a processor, the system comprising: a hybridheat transport module configured to be thermally coupled to theprocessor and to a fansink adapted to use forced air to remove heat fromthe processor, the hybrid heat transport module including: a pluralityof air channels adapted to receive the forced air from the fansink; anda fluid channel also adapted for removing heat from the processor,wherein the plurality of air channels are positioned over and around thefluid channel such that the fluid channel is substantially enclosedwithin the air channels.
 2. The system of claim 1, wherein the fluidchannel comprises an inlet and an outlet.
 3. The system of claim 2,further comprising a pump that is coupled to the inlet and the outlet ofthe fluid channel forming a closed loop channel.
 4. The system of claim3, wherein the pump is adapted for circulating the heat transfer fluidthrough the fluid channel.
 5. The system of claim 4, further comprisinga heat exchanger that is coupled between the outlet and the pump andconfigured to dissipate heat from the heat transfer fluid in the fluidchannel into an outside environment.
 6. The system of claim 1, whereinthe hybrid heat transport module is adapted for dissipating heat fromthe processor through air, through a fluid, or through both air andfluid.
 7. The system of claim 1, wherein the fansink comprises: a fanconfigured to force air through the at least one air channel of thefansink and the plurality of air channels; and the at least one airchannel that is adapted for removing heat from the processor, whereinthe fansink is coupled to a bottom plate.
 8. The system of claim 7,wherein the fansink and the hybrid heat transport module are adapted forsimultaneous operation.
 9. The system of claim 7, wherein the fansinkand the hybrid heat transport module are adapted for independentoperation.
 10. The system of claim 1, wherein the system is sized tocool a memory chip in addition to the processor.
 11. A method forcooling a processor, the method comprising the steps of: forcing airthrough a plurality of air channels to continually remove heat from theprocessor; monitoring a temperature of the processor; and circulating aheat transfer fluid in a fluid channel substantially enclosed within theplurality of air channels of a hybrid heat transport module that isthermally coupled to the processor to further remove heat from theprocessor when the processor reaches a threshold temperature.
 12. Themethod of claim 11, further comprising the step of ceasing to circulatethe heat transfer fluid through the fluid channel when the processor iscooled to a desired temperature.
 13. The method of claim 11, wherein thestep of circulating comprises turning on a pump that is coupled to thefluid channel to form a closed loop channel.
 14. The method of claim 13,further comprising the step of transporting the heat transfer fluidthrough a heat exchanger that is coupled between an outlet of the fluidchannel and the pump and adapted to dissipate heat from the heattransfer fluid into an outside environment.